1. Field
Embodiments relate to a 3-dimensional image display device and a method for designing a 3-dimensional image display device. More particularly, the embodiments relate to a method for forming a viewing zone, when a backlight panel, a parallax barrier or a lenticular lens for determining an advancing direction of light from the 3-dimensional image display device is inclined.
2. Description of the Related Art
To provide a 3-dimensional stereo image, different images should be provided to both eyes of an observer. For this, a 3-dimensional image display device may use a parallax barrier or a lenticular lens as a parallax separation means to separate an image provided to the left eye of the observer and an image provided to the right eye of the observer from each other. In other cases, a plurality of linear light sources may be arranged behind an image display panel having pixels to determine pixels to be provided to the left or right eye of the observer.
FIG. 1 is a diagram for illustrating a viewing zone formed by a 3-dimensional image display device. This is based on a case where a parallax barrier is applied as a parallax separation means. Referring to FIG. 1, light from a sub-pixel passes through an opening of the parallax barrier and forms a viewing zone at an optimum viewing distance (OVD). FIG. 1 shows a case of a multi-view 3-dimensional image display device which forms a common viewing zone at an optimum viewing distance. At this time, the common viewing zone may be formed by designing the parallax barrier so that a plurality of unit viewing zones forming sub-pixels are converged at a specific position. FIG. 1 depicts only a central viewing zone formed by the light passing through the parallax barrier from an image display panel where a viewpoint image is disposed. A side viewing zone (not shown) is presented adjacent to the central viewing zone.
FIG. 2 shows parallax barriers with different slopes. The parallax barrier depicted in FIG. 2A is configured so that unit parallax barriers extend in a vertical direction and are arranged in a horizontal direction. Meanwhile, the parallax barrier depicted in FIG. 2B is configured so that a unit parallax barrier has a slope from the vertical direction. Number (“1” to “6”) marked in a RGB sub-pixel represents viewpoint data which is mapped with the corresponding sub-pixel. In other words, the 3-dimensional image display device of FIGS. 2A and 2B may express six viewpoints, and third viewpoint image information recognized by an observer through an opening of the parallax barrier of FIG. 2A is arranged at blue (B) sub-pixels.
In case of the vertical parallax barrier depicted in FIG. 2A, at an optimum observation position (an OVD position in a depth direction and a central position of the viewing zone in a horizontal direction) of any one viewing zone, the light formed from a sub-pixel where image information of an adjacent viewpoint is disposed is not observed, and thus crosstalk between viewpoint images is ideally not generated. Also, even at a position deviated from the central position of the viewing zone, less crosstalk is generated between adjacent viewing zones in comparison to an inclined parallax barrier. However, chromatic dispersion occurs at each viewing zone since, for example, a third viewing zone is formed only in blue, and as the number of viewpoints increases, the resolution of a 3D image is deteriorated only in a horizontal direction.
Meanwhile, in case of an existing inclined parallax barrier as shown in FIG. 2B where a tilt angle is arcTan (⅓), two problems of a vertical parallax barrier as above may be solved. However, since a sub-pixel generally has a rectangular structure, even at an optimum observation position of the corresponding viewing zone, information of an adjacent viewing zone (for example, a second viewing zone and a fourth viewing zone in FIG. 2B) is provided to an observer together. In other words, crosstalk increases. In addition, in a 3D image display device designed with an inclined parallax barrier, severe Moire phenomenon is observed beyond the optimum viewing distance, and the quality of the 3D image deteriorates.
To solve the above problems, Korean Unexamined Patent Publication No. 10-2005-0025935 discloses that pixels are not arranged in a lattice pattern as shown in FIG. 3 but sub-pixels arranged in one row in a horizontal direction and sub-pixels arranged in an adjacent row are arranged alternately. In this case, even though a vertical lenticular lens is used, chromatic dispersion does not occur at each viewing zone. In addition, a deterioration ratio of resolution caused by increasing the number of viewpoints may be adjusted in both the horizontal direction and the vertical direction. However, this structure is not applicable to a general stripe-type horizontal RGB sub-pixel structure (where RGB sub-pixels are arranged in a lattice pattern, and one row of sub-pixels in a vertical direction are configured with sub-pixels of the same color) as shown in FIG. 2.
As another example using an inclined parallax barrier, Korean Unexamined Patent Publication No. 10-2011-0065982 discloses that a sub-pixel has a parallelogram shape having the same slope as the parallax barrier as shown in FIG. 4. In other words, in this structure, crosstalk is minimized by preventing information of an adjacent viewing zone from being provided to an observer at optimum observation position through the opening of the parallax barrier. However, this structure is also not applicable to a general stripe-type pixel structure, crosstalk is minimized only at a parallax barrier inclined with the same slope as the inclined structure, and a tilt angle of the inclined parallax barrier may not be changed as desired.
Meanwhile, in case of an existing general multi-view 3D image display device as shown in FIG. 5, a horizontal range in which all pixels of the image display panel are observable at an optimum viewing distance is formed narrowly in comparison to the width of the image display panel. Therefore, the degree of freedom in horizontal mobility of the observer is not so great even at the optimum viewing distance (L). In addition, if the observer is located at a border between the central viewing zone and the side viewing zone, a pseudoscopic image is observed. Moreover, even though the observer is within the central viewing zone, if the observer is beyond the optimum viewing distance, the degree of freedom in mobility in a horizontal direction is further restricted.